21730624 has 28 divisors (see below), whose sum is σ = 45660564. Its totient is φ = 10225664.

The previous prime is 21730559. The next prime is 21730637. The reversal of 21730624 is 42603712.

It can be written as a sum of positive squares in 2 ways, for example, as 12730624 + 9000000 = 3568^2 + 3000^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8899 + ... + 11074.

Almost surely, 2^21730624 is an apocalyptic number.

It is an amenable number.

21730624 is an abundant number, since it is smaller than the sum of its proper divisors (23929940).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21730624 is a wasteful number, since it uses less digits than its factorization.

21730624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20002 (or 19992 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 25.

The square root of 21730624 is about 4661.6117384441. The cubic root of 21730624 is about 279.0555937229.

The spelling of 21730624 in words is "twenty-one million, seven hundred thirty thousand, six hundred twenty-four".